Vintage Singer sewing machine thread take up arm assembly, compatible with the 401, 401A, 403, 403A, 404, 404A Slant-o-matic and the 500, 500A, 503, 503A Rocketeer. Mounting stud and screw included (this screw is reverse threaded to keep them from coming loose during use, so you will need to turn in the opposite direction to install them). Very good vintage condition, clean and rust free. Original, genuine Simanco parts - Assembly #172147, thread take up #172146 / #45824, stud #172145, screw #1130